Neuropsychiatric disorders such as autism, schizophrenia, bipolar disorder and intellectual disability are major burden to society. Our current knowledge of their underlying pathophysiology remains limited. However, a contribution of genetic factors has been clearly demonstrated. The goal of this study is to discover shared biological mechanisms between autism, schizophrenia and related disorders through investigation of the networks of interactions between proteins encoded by the high risk genetic factors implicated in these disorders. It is now firmly established that rare Copy Number Variants (CNVs): (1) play significant role in the risk of psychiatric disorders; (2) many high-risk CNVs cross disorder boundaries and are implicated in several psychiatric disorders. CNVs generally involve multiple genes, and how this large number of functionally heterogeneous genes contributes to the pathology is not completely understood. To advance our understanding of CNV contribution to psychiatric diseases, we propose to investigate how the genes from high risk rare CNVs interact on a protein level. The knowledge of the networks connecting CNV genes will help to better understand their pathological impact in different disorders. Using the constructed networks, we will test the hypotheses that: (1) cross-disorder CNVs share interacting protein partners that may explain shared etiology of different disorders; (2) cross-disorder CNVs have a unique set of interacting partners that may explain the differences between disorders. We have selected 11 high risk CNVs (containing 169 genes) that are firmly implicated in two or more psychiatric disorders for this study. Literature search fr binary protein-protein interactions (PPIs) for these 169 genes demonstrated that 33% of them have no PPIs annotated in the public databases, and only 3.5% of them interact with each other. However, it has been repeatedly demonstrated that literature PPIs are biased toward highly studied proteins, incomplete, and often are not as reliable as commonly assumed. Here, we are proposing to perform an unbiased protein interaction screen for 169 genes from high risk cross-disorder CNVs. Our Specific Aims are as follows: (1) Assemble a library of 169 open reading frame (ORF) clones corresponding to genes from 11 CNVs that confer high risk to psychiatric disorders; (2) Build and validate the cross-disorder CNV interactome; (3) Identify and perform follow-up functional studies of the interacting partners that are shared by or are unique to cross-disorder CNVs.